1. Field of the Invention
The present invention relates generally to wallpapering, and more specifically, to a knife guide for cutting wallpaper at any vertical inside corner of a room.
2. Description of the Related Art
Wallpapering an inside corner of a room presents a technically difficult problem in that it is visually desirable to have a sharp right angle with the pattern or print of the wallpaper matching as it turns the corner. Unfortunately, it is very difficult to construct a perfect corner. Thus, where a perfect corner would have intersecting planes of two right-angled walls forming a perfectly straight vertical line, in reality, the intersecting planes form generally non-linear and multi-planar lines. This makes it nearly impossible for the artisan to go around the corner with a single sheet of paper finishing one wall and starting down the next with a perfectly plumb vertical edge. It is also nearly impossible to have two side edges of paper meet of butt together at the corner as one would on the flat wall.
A second reason for "breaking" and restarting at every inside corner is that some materials shrink upon drying. This ofter ruins the tight bond at the inside corner and the sharp, crisp look of a 90-degree angle.
Although overlapping a side edge portion of one sheet over the side edge portion of the other sheet is a known technique for compensating for imperfections in the corner, creating the necessary overlap which looks best is difficult. It should be very small, e.g. 1/8" at most, just enough to hide a seam at the very corner and giving the illusion of the pieces being butted together.
Another great benefit of making the overlap small occurs with printed papers that require the pattern always be matched. With the small overlap, the cut piece can be matched at eye level and then made vertically plumb overall. The illusion created is that it is a perfect match at the corner and no material is lost or wasted.
Various known devices have been used in the past to guide a wallpaper knife. For instance, U.S. Pat. No. 3,500,540 has a right-angled guide for holding a wallpaper knife in the corner of the guide in order to guide the knife down the corner of a room. However, the guide requires a perfect corner in order to cut wallpaper in a straight line at the corner. Therefore, U.S. Pat. No. 3,500,540 does not address the problems in wallpapering created by imperfect room corners.
U.S. Pat. No. 3,875,664 describes a scribing tool for cutting tile which must be cut next to a wall. However, since tilts are rigid, they do not experience the same problems associated with cutting wallpaper sheets.
U.S. Pat. No. 4,330,939 describes a template for trimming covered linoleum.
U.S. Pat. No. 3,724,010 describes a device which resembles a putty knife having a knife blade mounted in a forward corner edge thereof.
U.S. Pat. No. 4,589,207 describes a wallpaper trimmer which does not have any specific application for overlapping two sheets of wallpaper
U.S. Pat. No. 4,095,340 teaches a device for trimming overlapping edges to form a butt-seam.
U.S. Pat. No. 4,667,409 describes a wallpaper trimmer for cutting wall coverings on outer wall corners.
The above-mentioned patents do not address problems created by inperfect wall corners.